1. Field of the Invention
The present invention relates to a display device.
2. Description of the Related Art
In a display device using a light emitting element, such as an organic EL (electro luminescence) element, the light emitting element is controlled by using thin film transistors. Further, it is known that the light emitting element emits white light and a color filter is used to perform full-color display (JP 2008-511100 A). The color filter typically includes a black matrix.
The pixel electrodes of the light emitting element are connected via contact holes to the thin film transistors below the co holes. Since each of the contact holes is a void, no light emitting element is allowed to be formed on the contact hole. A light emitting area therefore often has a shape that avoids the corresponding contact hole, for example, a rectangular shape with part thereof cut off. In this case, when all light emitting areas, each of which has long sides and short sides, are arranged in the same orientation, the long sides, where light intensity is higher, are undesirably aligned with one another, resulting in degradation in display characteristics. JP 2015-108751 A discloses that a plurality of light emitting areas are so arranged as to be oriented differently.
A light emitting element is formed of a plurality of layers, and in a case where any of the layers is made of a metal, external light is reflected off the surface of the metal layer or the interface between the metal layer and a layer adjacent thereto. In a case where these reflection surfaces incline or have irregularities, the reflected light is visible when the screen of a display device using the light emitting element is viewed in an oblique direction. In a case where each light emitting area of the light emitting element has a shape having horizontal and vertical lengths different from each other, the intensity of the reflected light varies depending on the direction in which the reflected light is viewed. In a case where the light emitting areas are shifted from the openings of the black matrix, the portions of the black matrix that block the light emitting areas appear to be large or small depending on the viewing direction. The external light incident on the light emitting element is reflected off the contact holes, and the direction in which intense reflected light is visible varies depending on the positions of the contact holes relative to the light emitting areas.
In particular, light emitting areas oriented differently on a color basis cause the intensity of the reflected light to vary on a color basis, resulting in a problem of different luminance and tint to be viewed depending on the viewing direction.